The endoscopic treatment of lesions presently encompasses a variety of techniques such as electrocauterization, laser photocoagulation, heat therapy by the application of heat probes, and sclerotherapy which involves the injection of medicine into a target varix by a needle passed through the working channel of the endoscope. A further, widely used and increasingly promising technique involves the ligation of lesions, wherein mucosal and submucosal tissue is strangulated by an elastic ligature.
A variety of instruments for effecting the ligation of body tissue by the application of an elastic ring are well known in the prior art. Some of these instruments, because of their rigidity and size are suited only for treatment of lesions that are in the external regions of the body or in the shallow body cavities. Others are particularly suited for the ligation of tissue in the abdominal cavity, such as for tubal ligation, when the abdominal cavity has been opened surgically.
U.S. Pat. No. 3,760,810 to Van Hoorn discloses an endoscope-equipped instrument comprising a device with two tubes mounted one inside the other, with the inner tube protruding at the front of the outer tube. Means are included to move the outer tube forwardly relative to the inner tube and cause an elastic cord to be dislodged and placed about the tissue to be ligated. In U.S. Pat. No. 4,257,419, there is disclosed an instrument for ligating hemorrhoids wherein a suction tube fitted inside a proctoscope provides means for sucking the hemorrhoid into a suction cavity where a ligating ring is applied. Both of these instruments are rigid devices suited for treating lesions close to the external regions, and both are equipped with only a single elastic ring for treating a single lesion.
There are also instruments in the prior art which employ laparoscope-assisted means for ring ligation such as shown in U.S. Pat. No. 4,257,420 and 4,471,766, wherein the instruments are each equipped with a single elastic band and utilize forceps to position the tissue for ring ligation.
In U.S. Pat. No. 3,870,048, there is disclosed a ring applicator device having forceps slidably mounted in a cylinder for grasping the fallopian tube and including means for displacing an elastic ring to effect a ligation of tissue. While this device can be equipped with a plurality of elastic rings, it's rigidity precludes its use with a flexible endoscope for treating the deeper regions of an internal organ, such as the alimentary tract.
A flexible endoscopic instrument used for ligation purposes and disclosed in U.S. Pat. No. 4,735,194 comprises a flexible fiberoptic endoscope on the end of which is secured an outer tube and an inner tube reciprocally movable therein. A trip wire is fastened to the inner tube to provide rearward motion to the inner tube to cause an elastic ring fitted about the inner tube to slide off and effect ligation. While this instrument is suitable for ligating lesions deep within the alimentary tract, it can only be used to treat but one lesion during a single insertion of the instrument.
In many instances, however, there are a number of lesions present in the organ being treated, such as the esophagus, stomach or colon. If an endoscopic instrument equipped with only one elastic ring is used, the treatment of multiple lesions in the same organ requires the extraction of the endoscope after the placing of each elastic ring about a lesion and reinsertion of the endoscope into the organ to repeat the procedure for placing an elastic ligating ring about each of the lesions. In addition to being time consuming and an associated concern for blood loss when there are bleeding lesions, there are other disadvantages associated with the repetitions of this procedure. The instrument, when withdrawn from the body, is usually covered with blood and mucous. Furthermore, each time the instrument is reinserted into the organ, it becomes necessary to relocate a lesion to be treated and to orient the instrument with respect thereto. In some cases where considerable blood and mucous are present, the relocating of the instrument is a tedious and difficult task.